Significant body weight loss was observed in rats 8 weeks after total gastrectomy. Peripheral blood from rat tail vein at this time was examined and decreases of hemoglobin, hematocrit values, plasma proteins and also marked increase of reticulocytes were observed. Especially, immature erythrocytes which were not observed in normal rats appeared in the blood of the totally gastrectomized rats. Methylcobalamin (CH_3-B_12) 50μg/100g or 250μg/100g and cyanocobalamin (CN-B_<12>) 250μg/100g were subcutaneously injected to the rats daily from 8th week till 12th week after the operation, and their effects on the agastric anemia were examined. Reticulocyte contents and plasma proteins were repaired to some extent in CH_3-B_<12> 250μg/100g treated group. CH_3-B_<12> 50μg/100g or CN-B_<12> 250μg/100g also showed a tendency of repairment, but not significantly. On immature erythrocytes, marked decreasing effects were observed in both CH_3-B_<12> and CN-B_<12> treated groups. Particularly, 250μg/100g of CH_3-B_<12> was the most effective and 50μg/100g was the second. 250μg/100g of CN-B_<12> was also significantly effective compared with the placebo control, though its effects was inferior to that of 50μg of CH_3-B_<12>.